1. Field of the Invention
This invention concerns a new highly crosslinked silicone polymer particle for gas chromatography application and a process and method for synthesizing such polymer. The new copolymer comprises vinyltriethoxysilane and octadecyltrichlorosilane. In particular, this invention concerns a polymer having a high degree of crosslinking and a good balance of polar to nonpolar sites in the porous silicon polymer resulting in a good separation of compounds of variable polarity. The new polymer also prevents bleeding or tailing of the stationary phase.
2. Related Disclosures
Gas and liquid chromatography columns for separation and analyses of the solutes of liquid samples have long been known and used in research and industry. Gas chromatography has also been successfully employed in the space projects. Both the Viking and Pioneer Venus missions had gas chromatograph on board and used it for analyses of various samples of atmosphere and surface materials. Gas chromatography has also been proposed for use in certain future missions, such as Comet Rendezvous Asteroid Flyby and Cassini Saturn Mission which require the precise determination of polar and nonpolar chemicals in minuscule amounts.
For these missions, a highly sensitive detector spectrometer combination consisting of metastable ionization detector and ion mobility spectrometer was developed. This detector, however, is extremely sensitive to column bleed associated with the conventional liquid phases coated on solid supports. Chromatograms using these detectors with column containing liquid phases on solid support are usually very noisy, having a rough base line. While silicone liquid phases on solid supports are known to provide good separations of polar as well as non- polar compounds, the bleeding problem usually persists.
It would thus be very useful to have available a material which would avoid the bleeding problems but still provide a good separation of polar and non-polar compounds.
Many chromatographic support materials have been developed with time. U.S. Pat. No. 4,767,529 describes nitro group-containing modified chromatographic support material and discusses in general the use of a globular, hydrophilic vinyl polymer modified with m-aminophenylboric acid after epoxidation. These vinyl polymers have a high mechanical and chemical stability and good compatibility with organic solvents.
U.S. Pat. No. 4,446,105 describes the use of octadecylsilane and cyano propylsilane as absorbents in chromatographic columns particularly suitable to identify hydrocarbon components of fuels produced by liquefaction of coal.
U.S. Pat. No. 4,045,353 discloses a solid chromatography support which has a high separation ability, accommodates a high load of the sample and does not cause the elution of a polymer. The solid support is prepared by the absorption of polymerizable monomer onto a micro-porous inorganic substrate. The suitable monomers include ethylenically unsaturated monomers such as styrene monomers, fluorine monomers, such as tetrafluoroethylene, silicon containing monomers such as vinyltriethoxysilane, acrylates or other vinyl monomers.
U.S. Pat. No. 3,878,092 relates to chromatographic analyzers utilizing a chromatographic column which column is provided with a partitioning agent comprising a crosslinked polymeric material bonded to an interior of the column either directly or through an intermediate film or coupling agent. The coupling agent, which may be vinyltriethoxysilane, is used to coat the interior wall surface of the chromatographic column and must have reactive groups capable of chemically reacting with the column wall.
Vinyltriethoxysilane used as silylating agent is described in U.S. Pat. No. 4,732,887. A process for preparation of octadecyltrichlorosilane is disclosed in U.S Pat. No. 3,666,530 and its use in preparation of a reverse-phase chromatographic packing is disclosed in U.S. Pat. No. 4,324,689.
While some of these patents contain some improvements with respect to their intended utilities, none does achieve a polymer having properties most desirable for space use, demanding the highest degree of accuracy in shortest possible time.
It is, therefore, a primary object of this invention to prepare a gas chromatography column packing (stationary phase) which would avoid the bleeding problems but have a good separation of a wide variety of compounds of variable polarities. The new polymer having octadecyltrichlorosilane and vinyltriethoxysilane as starting comonomers produce uncrosslinked intermediate polymer, which is then crosslinked to produce the crosslinked, porous, polymer particle which is insoluble in most organic solvents, of the present invention having such qualities.